Pratik Dhungana(BGE/070)
Survey Officer
Remote Sensing and Photogrammetry Section
Survey Department, Kathmandu
First of all, what is a map?
 Map:
 A scaled, simplified and symbolized representation of whole or part of earth via the
method of projection.
 All maps are falsified (distorted) representation of reality, but good maps are those
where falsification is purposeful and meaningful
 Cartography:
 The art and science of map making
 Topography:
 Representation of land form and the features on land surface
 Topographic map:
 A 2-D representation of the earth's 3D landscape, where details of topography, artificial
and natural features are accurately represented
 Extremely important for planning and implementing engineering and development
projects
 It shows natural features like waterbodies, streams, ridges, forests, hills, mountains etc
 Mand-made features like road network, utility lines, various types of religious and
functional buildings etc
 Additional information like place and feature names
 Topography is represented with the help of contours
 Base map
 a map showing features of different themes and thus serves as a base to derive various
thematic maps
 Topographic maps of Nepal:
 Prepared by the Survey Deparment (SD) of Nepal—the only National Mapping
Organization (NMO)
 Scale of 1:25K, 1:50K
 Prior 1989, small scale topographic maps were prepared with
international support and cooperation.
 1930
 Scale of 1 inch = 4 mile
 26 map sheets covering whole Nepal made by Survey of India.
 1950
 Scale of 1: 250000
 17 map sheets made by US Army
 1970
 Scale of 1 inch = 1 mile
 266 map sheets covering whole Nepal made by Survey of India.
 1977
 Scale of 1:200000
 Map Sheets covering whole Nepal made by Russian Government
 1989-1992
 Lumbini Zone Mapping Project
 81 map sheets covering Lumbini Zone of Nepal in a scale of 1:25000
 Prepared by Survey Department, Nepal with technical and financial
support of Government of Japan through Japan International
Cooperative Agency (JICA)
 1992-1996
 Eastern Nepal Topographic Mapping Project
 255 map sheets in a scale of 1:25000 for tarai and middle mountains
and 37 map sheets in a scale of 1:50000 for high mountains and
himalayan region covering eastern Nepal .
 Prepared by Survey Department, Nepal with technical and financial
support of Government of Finland through Finnish International
Development Agency (FINNIDA)
 1996-2001
 Western Nepal Topographic Mapping Project
 254 map sheets in a scale of 1:25000 for tarai and middle mountains
and 79 map sheets in a scale of 1:50000 for high mountains and
himalayan region covering western Nepal except Lumbini zone.
 Prepared by Survey Department, Nepal with technical and financial
support of Government of Finland through Finnish International
Development Agency (FINNIDA)
 In 2001, topographic mapping of whole Nepal in a scale of
1:25000 and 1:50000 was completed.
 Total of 706 map sheets including 590 map sheets in 1:25000
scale and 116 map sheets of 1:50000 scale.
1 inch = 4 mile
1: 250000
1 inch = 1 mile
1:200000
 From 1989 to 2001traditional methods were used.
 Aerial Photography
 Aerial Photographs of 1989 for Lumbini zone Mapping Project
 Aerial Photographs of 1992 for Eastern Nepal Mapping Project
 Aerial Photographs of 1996 for Western Nepal Mapping Project
 Stereo pair photographs covering entire mapping area were
collected
 Stereoscopic Feature Extraction
 Aerial Triangulation and Orientation image on stereo plotter for the
stereoscopic vision
 Stereoscopic vision enables the 3D visualization in stereo pair
 Plotting line features, polygon features, point features, and
contours.
Stereoplanigraph, Kelsh or PG-2
stereoplotter (Figure 3) (USGS,
1960).
• National Topographic Database(NTDB) is prepared
from scanned topographic maps prepared under
LMP, ENTMP and WNTMP.
• Georeferencing of Scanned Map sheet
• Onscreen Digitization
• Result: Digital topographic database
Preparation of National Topographic Database
• Acquire Images for target area
• Select most recent images with minimum cloud coverage
• Select suitable well distributed control points in images,
preferably in overlapping areas of multiple images
• Make use of existing topographic maps, Images and
sources like OSM and GoogleMaps for planning
• Orthorectification using corresponding rpc file and ALOS-
PALSAR DEM, to remove distortion due to tilt and terrain.
• Pansharpening of high resolution panchromatic image with low
resolution multispecral image to obtain high resolution
multispectral image.
• Georeferencing of pansharpened image with ground control
points obtained via DGPS.
• Update existing NTDB digital database based on georeferenced
image.
• Features are extracted by onscreen digitization and categorized
as per specification, based of image.
• Only planimetric details are taken. These features are to be
verified and modified as per field verification.
• Verification of Place names & texts and collection of
names to be changed.
• Verification of features category
• Collection of data on location, category and other
required characteristics of various infrastructures
• Necessary changes are made in the database as per field
verification.
• After database is updated, cartographic work begins.
• Symbolization of features by their categories and then
generalization .
• Making necessary alteration in position and size of annotations.
• Preparing map layout, test printing and necessary modification.
• After thorough checking, mass reproduction of map is done
using Computer to Plate technology.
